Community access television, or cable television, (CATV) networks use an infrastructure of interconnected coaxial cables, splitters, amplifiers, filters, trunk lines, cable taps, drop lines and other signal-conducting devices to supply and distribute “downstream” signals from a main signal distribution facility, known as a head-end, toward subscriber premises such as homes and businesses. The downstream signals operate the subscriber equipment, such as television sets, telephones, and computers. The typical CATV network is a two-way communication system. CATV networks also transmit “upstream” signals from the subscriber equipment back to the head-end of the CATV network. For example, upstream bandwidth may include data related to video-on-demand services, such as video requests and billing authorization. Two-way communication is also utilized when using a personal computer connected through the CATV infrastructure to the public Internet, for example when sharing photo albums or entering user account information. In yet another example, Voice over Internet Protocol (VoIP) telephones and security monitoring equipment use the CATV infrastructure and the public Internet as the communication medium for transmitting two-way telephone conversations and monitoring functions.
To permit simultaneous communication of upstream and downstream CATV signals and the interoperability of the subscriber equipment and the equipment associated with the CATV network infrastructure outside of subscriber premises, the downstream and upstream CATV signals are confined to two different frequency bands. In most CATV networks the downstream frequency band, or downstream bandwidth, is within the range of 54-1002 megahertz (MHz) and the upstream frequency band, or upstream bandwidth, is within the range of 5-42 MHz.
An in-home entertainment (IHE) network may be coupled to the CATV network via the same coaxial cable delivering the downstream and upstream bandwidth of the CATV system. The in-home entertainment network can be a network providing multiple streams of high definition video and gaming entertainment. Examples of in-home entertainment network technologies include Ethernet, HomePlug, Home Phoneline Networking Alliance (HPNA), Multimedia over Coax Alliance (MoCA) and 802.11n protocols. The in-home entertainment (IHE) network is coupled to the CATV network within a subscriber premises to allow the CATV network to distribute IHE signals from one multimedia device to another within the subscriber premises.
Since the operation of the subscriber premises IHE network must occur simultaneously with the operation of the CATV services, the IHE signals often utilize a frequency range different from the frequency ranges of the CATV upstream and downstream signals. A typical IHE frequency band is 1125-1675 MHz, which is referred to in this document as the multimedia-over-coax frequency range, or bandwidth. In this document multimedia-over-coax signals are IHE signals within this frequency range. A specific IHE network technology can includes other frequency ranges, but the 1125 to 1675 MHz frequency range is of major relevance because of its principal use in establishing connections between the multimedia devices within a subscriber network.
Although using the in-home cable infrastructure as the communication medium substantially simplifies the implementation of the IHE network, there are certain disadvantages to doing so. One noted problem arises when multimedia-over-coax signals pass backwards through a conventional splitter en route to another IHE-enabled device within the network. The CATV network and the in-home cable infrastructure were originally intended for the distribution of CATV signals. The typical in-home cable infrastructure uses signal splitters to divide CATV downstream signals into multiple CATV downstream paths and to combine multiple CATV upstream signals into a single CATV upstream path. The CATV entry adapter was not originally intended to communicate multimedia-over-coax signals between its ports, as is necessary to achieve multimedia-over-coax signal communication in the IHE network. To implement the IHE network, the multimedia-over-coax signals must traverse between separate signal component legs of a signal splitter/combiner which are connected to the multiple ports.
The typical signal splitter has a high degree of signal rejection or isolation between its separate output signal component legs. When the multimedia-over-coax signals traverse between the separate signal component legs of the splitter, the degree of signal rejection or isolation greatly attenuates the strength of the multimedia-over-coax signals. According to field tests, IHE devices coupled to output ports of a two, three, or four-way signal splitter are able to communicate in the multimedia-over-coax frequency band. However, IHE-compatible devices coupled to the output ports of multi-port splitters such as six-way and eight-way signal splitters are having trouble communicating using multimedia-over-coax signals. For splitters having more than four output ports, the splitters must have special circuitry to overcome communication problems in the multimedia-over-coax band. Thus it is desirable to have a system which transmits both CATV and IHE signals without attenuating or rejecting the IHE signals that are travelling between splitter output ports.